Group vi{14 b transition metal-amino-phosphorodithioates in lubricating oil

ABSTRACT

Group VI-B transition metal-amino-phosphorodithioates, which are the reaction products of amine salts of Group VI-B oxyacids and phosphorodithioic acids, are disclosed. A process for producing the beforementioned compounds is also disclosed that comprises contacting an acidic aqueous medium containing the Group VI-B metal source with a water-immiscible organic medium containing an alkyl amine and reacting said product with a phosphorodithioic acid and recovering the compounds of this invention. Lubricating compositions containing the compounds of this invention are also disclosed.

a Unite States Patet [151 3,664,954 Chiola et a]. 5] y 23, 1972 [54]GROUP VI-B TRANSITION METAL- 3,193,500 7/1965 Hartle ..252 32.7ANflNO-PHOSPHORODITHIOATES IN 3,290,245 12/ I966 Elliott et al......252/32.7 LUBRCATNG OIL iiii'li? 1351333 2 2 5251533 evu as [72]Inventors: Vincent Chiola, Towanda; Phyllis R.

Dodds, wysox both of Primary Examiner-Daniel E. Wyman [73] Assignee:Sylvania Electric Products Inc. Assistant Examiner-L VaughnAttorneyNorman J. OMalley, Donald R. Castle and William [22] Filed! Apr.1, 1970 H McNeil] [21] App1.No.: 24,793 57] BS CT A TRA R l ted U.S.Alicat' nData e 8 pp m Group Vl-B transitionmetal-amino-phosphorodithioates, Dlvlslon 0f P 1968, which are thereaction products of amine salts of Group Vl-B 3,598,848. oxyacids andphosphorodithioic acids, are disclosed. A process for producing thebeforementioned compounds is also "252/32'7 313 4 disclosed thatcomprises contacting an acidic aqueous medin m urn containing the GroupVI-B metal source with a water-im- [58] Field of Search ..252/32.7 E,389,400 miscible organic medium containing an alkyl amine and reach ingsaid product with a phosphorodithioic acid and recovering [56]References Cited the compounds of this invention. Lubricatingcompositions UNITED STATES PATENTS containing the compounds of thisinvention are also disclosed.

2,737,492 3/1956 Beegle et a]. ..252/32.7 4 Claims, No Drawings GROUPVI-B TRANSITION METAL-AMINO- PHOSPHORODITI-IIOATES IN LUBRICATING OILCROSS REFERENCE TO RELATED APPLICATION This application is a division ofSer. No. 757,788 filed September 5, 1968, now U.S. Pat. No. 3,598,848issued on Aug. 10, 1971 and assigned to the assignee of the presentinvention.

BACKGROUND OF THE INVENTION This invention relates to oil-soluble GroupVl-B transition metal-amino-phosphorodithioates, to processes forproducing same and to lubricating oil compositions containing thecompounds.

Present day lubricating oils and greases contain various additives thatimpart to the compositions desirable characteristics such as detergency,antioxidant, antisludge, anticorrosion and antiwear properties. Toachieve a suitable composition several additives generally have to beadded. For example, zinc dialkyldithiophosphates, which are produced byneutralizing the reaction product of phosphorus pentasulfide and analcohol with sodium hydroxide and thereafter replacing the sodium ionswith zinc ions in an aqueous medium impart some of the abovecharacteristics such as antioxidant, antiwear and anticorrosionactivity. Other materials such as the amine salts of molybdic ortungstic acid are used to impart sludge dispersancy, high-temperaturedetergency and antifriction properties. Other additives which are usedinclude the adducts of the zinc phosphorothioates and alkylene oxidessuch as the lower alkylene oxides having an alkylene radical containingsix or less carbon atoms. The materials are used to impart improveddetergency and corrosion resistance to the oil composition. In eachinstance, however, more than one additive is required to achieve many ofthe desired characteristics. It is believed, therefore, that an additivecontaining more of the desired properties in a single compound therebyreducing the number of additives required is an advancement in the art.Furthermore, it is believed that the process for producing suchcompounds, due to its flexibility and simplicity, is also an advancementin the art.

SUMMARY OF THE INVENTION In accordance with one aspect of thisinvention, there is provided new compositions which are the reactionproducts of the amine salts of the various Group VI-B oxyacids and thecompounds ofthe formula I R OPSH Formula 1 wherein R and R are eachhydrocarbon radicals selected from the group consisting of alkyl, aryland alkaryl, having from about one to about 30 carbon atoms.

A second aspect of this invention is the process for preparing saidcompounds. The process is relatively free of operating difficulties andhas a large degree of flexibility, and in general, involves l.contacting an aqueous medium comprising water and a water-soluble GroupVl-B transition metal source, said medium being at a pH of below 7,preferably at a pH of from about 0 to about 4, with a water-immiscibleorganic medium comprising a water-immiscible solvent and an alkyl amine,for a time sufficient to extract at least some of the transition metalfrom the aqueous medium into the organic medium thereby forming anamino-Group VI-B transition metal reaction product;

2. separating the organic and aqueous mediums;

3. recovering the Group VI-B transition metal-aminophosphorodithioiccomposition by providing the following steps, in any order:

a. adding a phosphorodithioic acid to the amino-Group Vl-B transitionmetal reaction product, and

b. removing the organic, water-immiscible solvent from the organicmedium thereby recovering the compounds of this invention.

If desired, the process of this invention can be carried out in adifferent sequence of operating steps with equally good results.Therefore, in accordance with another embodiment of this invention, anaqueous medium comprising water and Group Vl-B transition metal sourceis contacted with a waterimmiscible organic medium comprising awater-immiscible organic solvent, an alkyl amine and phosphorodithioicacid. An additional aspect of this invention is a lubricatingcomposition containing the amino-Group VI-B transition metalphosphorodithioiccompositions in specified amounts.

For a better understanding of the present invention. together with otherand further objects, advantages and capabilities thereof, reference ismade to the following disclosure and appended claims in connection withthe above description of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The weight percentage of theGroup Vl-B transition metal can be varied depending upon the quantity ofGroup VI-B transition metal desired in the additive and will bedependent upon the amount of the foregoing metal present in the aqueoussolution and the amount of the dialkyl phosphorodithioic acid used inthe process. For example, the molybdenum containing compositions of thepresent invention will generally contain from about 6-10 percent byweight of sulfur, 24 percent by weight of phosphorus, 2-7 percent byweight of molybdenum and from 1-2 percent nitrogen. The weightpercentages of the foregoing components will vary depending upon themolecular weight of the Group Vl-B transition metal that is used. Forexample, the foregoing compositions wherein tungsten is the Group Vl-Btransition metal, will contain from about 4 to about 7 percent sulfur,about l-3 percent phosphorus, about 2-13 percent tungsten and from about0.5 to 1.5 percent nitrogen. With chromium-containing compositions theweight percentage of chromium is decreased with the correspondingincrease in the other elements due to its lower molecular weight. TheGroup Vl-B transition metal containing radical will in most instances bythe transition metallic oxycations represented by the formula M ,0,wherein M is the Group VIB transition metal, x is an integer from l-30,y is an integer from l-9O and the valence of M ,.O,, is from 1 to 15.The compounds of this invention, therefore, enable a large degree offlexibility which was heretofore only achieved by blending severaladditives.

Lubricating oils which can be used as the base oils to which the newcompounds of this invention are added are not limited as far as theeffectiveness of the compounds are concerned, therefore, lubricationoils that are of a lubricating viscosity can be used. For example, oilsthat have a naphthenic base, paraffinic base and other hydrocarbonbases, as well as lubricating oils derived from coal products andsynthetic oils, such as the alkylene polymers, alkylene oxide polymers,dicarboxylic acid esters, alkylated benezene, silicate esters, siliconpolymers and the like are suitable.

In general, any water-soluble Group Vl-B transition metal source can beused, that is a material which contains chromium, molybdenum or tungstenand that is soluble to the extent of at least 0.1 grams per grams ofwater at 25 C. Suitable sources of Group VI-B transition metals includewater-soluble Group Vl-B transition metal oxides, Group Vl-B transitionmetal oxyhalo compounds, Group Vl-B transition metal peroxy compounds,ammonium and alkali metal salts of Group VI-B transition metalperoxyacids. The alkali metal salts of the Group VI-B transition metalperoxyacids, such as sodium, potassium and lithium molybdates, sodiumpotassium and lithium tungstates and the like, are preferred with thesodium salts being especially preferred. Although any of the Group VI-Btransition metals, that is either chromium, molybdenum or tungsten canbe used, molybdenum and tungsten are preferred.

In most instances, an aqueous solution having a Group VI-B transitionmetal concentration of from about I percent to about percent by weightis preferred. In some instances concentrations of as low as about 0.1percent by weight can be used, however, these lower concentrations arenot preferred since there are no additional beneficial results achievedfrom using the lower concentrations and the excess water can createdisposal problems. Although higher concentrations can be used such asthose containing a metal concentration greater than about percent byweight, such high concentrations generally approach saturated solutionswhich can result in either a yield loss or require recycle of theaqueous medium. The pH of the aqueous medium is below about 7 with a pHof from about 0 to about 4 being preferred in most instances. Use of ahigher pH prevents extraction and formation of the compounds of thisinvention.

The phosphorodithioic acids which can be used in practice of thisinvention are well known in the lubricating art and in general containtwo hydrocarbon radicals selected from the group consisting of alkyl,aryl and alkaryl and from about one to about 30 carbon atoms. As isknown in the art, since the phosphorodithioic acids are often preparedfrom mixtures of alcohols and phosphorus pentasulfide, the carbon atomcontent of the hydrocarbon group is an average value for the mixture.For example, one of the preferred phosphorodithioic acids is one inwhich the hydrocarbon radicals are alkyl groups having an average chainlength of about five carbonatoms. In some instances, however, relativelypure phosphorodithioic acids are produced and these are also good rawmaterials. For example, one of the preferred raw materials is di-isoctylphosphorodithioic acid.

When the amines are described herein as being water-insoluble, it meantthat less than about 0.1 grams will dissolve in 100cc of water at 25 C.When the amines are described herein as soluble in the water-immiscibleorganic solvent, it is meant that greater than about 0.1 grams, willdissolve in 100cc of the organic solvent at 25 C. The amines which aresuitable, therefore, are the alkyl amines that are soluble in awater-immiscible, organic solvent of a class to be hereinafter describedand insoluble in water. These useful amines are alkyl amines selectedfrom those ofthe formula R Formula 2 wherein R R and R are each selectedfrom the group consisting of hydrogen and alkyl containing from aboutthree to about 30 carbon atoms and wherein at least one of R R and R isalkyl and the total number of carbon atoms is from about three to about60 carbon atoms. The alkyl groups can be either straight or branchedchain and can be a mixture of compounds containing alkyl radicals ofvarying chain lengths but having a given average value. The amines asdescribed above can be either primary, secondary or tertiary amines. Forexample, suitable primary amines include trialkyl-methyl amines of theformula R.n Formula 3 wherein R R, and R are each alkyl radicalscontaining from one to about carbon atoms. Typical commerciallyavailable amines of the above class are those wherein two of theradicals represented by R R and R in Formula 3 above are methyl and theother radical can vary from about 15 to about 21 carbon atoms.

Suitable secondary alkyl amines that are water-insoluble and organicsolvent soluble are selected from amines of the formula RI! RI -IHFormula 4 wherein R and R" are each alkyl containing from three to 30carbon atoms. For example, a commercially available suitable amine is anamine wherein R is an alkyl radical containing from about 11 to about 14carbon atoms and R is an undecyl radical.

Tertiary amines, that is those of the formula R -Ik-R; Formula 5 whereinR R, and R, are each alkyl radicals containing from about three to about30 carbon atoms. The R groups can be either straight or branched chainand can be the same or different radicals. Commercially available aminesinclude those of Formula 5 wherein R R and R, each vary from about eightto about 13 carbon atoms.

It has been found that the volumetric ratio of the amine to the solventin the organic medium should be between about 10:90 to about :10. Use ofhigher and lower concentrations reduces the efiiciency of the process,therefore, are not generally used.

The organic solvents which can be used in the practice of this are thosethat are essentially immiscible withwater, that is those that have asolubility of less than 0.1 grams of solvent/cc of water at 25 C. andhave a boiling point less than about 250 C. In most instances thearomatic organic solvents, that are immiscible with water, such asbenzene, toluene, cumene, xylene, napthalene and other petroleumfractions containing aromatichydrocarbons that have boiling points belowabout 250 C., ,will be used.'lf desired, however, the solvent can beselected from the cycloparaffins that have the foregoingwater-immiscible and boiling point properties, such as cyclohexane,cyclopentane and the like. Although the solvent can have a boiling pointas high as 250 C., since the solvent is subsequently removed from thecompounds of the present invention, normally by distillation, it ispreferred to use solvents having relatively low boiling points, that isbelow about 150 C. with those having a boiling point of below about C.being especial preferred. Since the process is carried out in liquidphase, in order to avoid potential losses of solvent or the use ofpressurized equipment, it is generally preferred to use solvents havinga boiling point above about 50 C.

The time the aqueous and organic media are in contact is immaterial froman operative standpoint, however, in order to achieve relatively highyield, without recycle, the contact time should be sufficient to extractessentially all of the Group VI-B transition metal into the organicphase. In most instances, when the aqueous solution concentration oftransition metal is within the preferred range as heretofore specified,the length of contact is not excessive, that is generally below about 10hours. Since the organic and aqueous media are readily separable, it isgenerally relatively simple to determine if the extraction is complete.For example, after the organic and aqueous media have been in contactfor a reasonable period of time, that is, longer than about 30 minutes,the two media can be allowed to separate by allowing them to standwithout agitation and then sample one of the media and analyze for thepresence of the transition metal. In most instances the aqueous mediumwill be analyzed to determine the degree of extraction that hasoccurred. As previously mentioned, the organic and aqueous mediaseparate easily, therefore conventional techniques for the separation ofimmiscible liquids can be used such as gravity separating, decanting andthe like.

After the two media are separated, the phosphorodithioic acid can beadded either to the organic medium and thereafter the solvent removed orthe solvent can be removed before the addition of the phosphorodithioicacids. In most instances it is preferred to add the acid prior toremoval of the solvent because the amino-transition metal salts arerelatively viscous. In most instances distillation will be the preferredmethod of removing the organic solvent for either media. As can beappreciated the solvent can be condensed and recycled if desired.

To further illustrate certain embodiments of the present in vention, thefollowing non-limiting examples are presented. All parts, proportionsand percentages are by weight unless otherwise indicated.

EXAMPLE 1 Four solutions containing 50, 60, 70, and 85 percent by volumeof a mixture of trialkyl straight chain symmetrical tertiary amines inbenzene are contacted with equal volumes of 3 M H 80 The amines mixtureis about 60 percent tridecyl amine and about 40 percent trioctyl amine.An aqueous solution of sodium tungstate is acidified to pH 2 withsulfuric acid. The concentration of tungsten in the aqueous solution isabout 200 grams/liter, W0 basis. Equal volumes of organic and aqueousphases are contacted for about 20 minutes. After settling, aliquots ofboth phases are taken and isotope studies showed 3 99 percent extractionof tungsten from the aqueous medium to the organic medium. The organicmedium is retained and the benzene is evaporated to isolate the activeingredient which is a viscous salt. The viscous salts are mixed withequal volumes of di-isoctyl phosphorodithioic acid and heated to obtainthe reaction between the salts and acid bath. The liquid product issoluble in W motor oil.

EXAMPLE 11 Organic solutions, A, B, and C containing 70 percent byvolume of three different amines in benzene are contacted with equalvolumes of 3 M H 80 The three amines used are given in the followingtable:

Solution Amine wherein the R groups are (3131121 having differentdegrees of branching.

The amine solutions are then contacted for about 30 minutes with equalvolumes of an aqueous solution of Na- WO,,, acidified to pH 2, withsulfuric acid and containing about 200g/liter, WO basis. After settling,the aqueous phases are analyzed for tungsten. About 210g/l W0 basis, isextracted into the organic media based upon the analysis of the aqueousphases. The amount of sulfur, as contained in the dithiophosphoricacids, needed to react with the tungsten in the organic media to form WSis calculated, and about 36 volumetric parts of a C-8 dialkylphosphorodithioic acid are added to volumetric parts of theamine-tungsten salts and gently heated. A 1 percent solution, by volume,is added to 10W motor oil. All are soluble and compatible with allcommercial motor oils.

EXAMPLE Ill Essentially the same procedure is used as in Example 1except that various phosphorodithioic acids are used in conjunction withvarious amines. Samples of the reaction product are D Amine as describedin Example 1 E A mixed dialkyl phosphorodithioic acid wherein the alkylgroups contain various chain lengths with an average value ofS carbonatoms in each alkyl grou "F= Di-isooctyl phosphorodithioic acid.

Infrared absorption spectra are obtained on each of the above samples.All samples have strong lines at 680, 980, 1,165, 1,380 and 2,940 cm.Samples 1 and 2 have two additional strong peaks at 1,520 and 1,620 cmand samples 3 and 4 have one additional strong peak at about 1,600. Theabove results indicate some differences in patterns when differentamines are used. For example, samples 1 and 2 were produced from aprimary amine. Samples 3 and 4 were produced from secondary amines,while samples 5-8 were produced from tertiary amines. Moderateabsorption peaks were attained on all samples at 670, 880, 1,205, 1,370,1,440, 1,500, 3,040 and 3,400 cm".

EXAMPLE IV Essentially the same procedure as in Example 111 is followedexcept that molecular equivalent amounts of sodium molybdate aresubstituted for the sodium tungstate. Samples of the reaction productsare analyzed for weight percent, S, P and Mo. Results of these analysisare given below.

Infrared absorption spectra are obtained on all samples. Strongabsorption peaks appear at 680, 980, 1,165, 1,470 and 2.940 cm".Moderate peaks appear at 600, 615, 710, 820, 870, 890, 1,040, 1,110,1,205, 1,440, 1,500, 1,560, 2,430, 2,880, 3,040 and 3,100 cm". The samestrong lines appear when primary and secondary amines are used as werepresent in Example 111.

EXAMPLE V Samples of lubricating oil compositions are prepared bydissolving about 10 percent by volume of the compositions prepared inExample Ill and IV in 10W motor oil. Samples of the above lubricatingcompositions when heated to about 120 C. for about 2 hours indicated nosludge formation. When heated in the presence of aluminum and leadindicate no corrosion of either metal. The above tests indicate theproperties which are suitable as additives for lubricating compositions.

The compositions of this invention will be used in amounts of less thanabout 10 percent by weight of the total lubricating composition. In mostinstances at least about 1 percent of the composition will be used. Itis also to be noted that often it can be advantageous to produce arelatively concentrated solution containing lubricating oil and a majoramount of the compositions of this invention then add this solution tothe lubricant to yield a mixture having the foregoing percentages byweight of the composition of this invention.

While there has been shown and described what is at present consideredthe preferred embodiments of the invention, it will be obvious to thoseskilled in the art that various changes and modifications may be madewithout departing from the scope of the invention as defined by theappended claims.

We claim:

1. A lubricating composition comprising a major amount of a mineral oilof lubricating viscosity and a minor efiective amount of atungsten-amino-phosphorodithioate having strong infrared absorptionpeaks at 680, 980, 1,165, 1,380 and 2,940 cm.

2. A lubricating composition according to claim 1 wherein saidtungsten-amino-phosphorodithioate is less than about 10 percent byweight to the total composition.

3. A lubricating composition comprising a major amount of a mineral oilof lubricating viscosity and a minor effective amount of amolybdenum-amino-phosphorodithioate having strong infrared absorptionpeaks at 680, 980, 1,165, 1,470 and 2,940 cm.

4. A lubricating composition according to claim 1 wherein saidmolybdenum-amino-phosphorodithioate is less than about 10 percent byweight to the total composition.

2. A lubricating composition according to claim 1 wherein saidtungsten-amino-phosphorodithioate is less than about 10 percent byweight to the total composition.
 3. A lubricating composition comprisinga major amount of a mineral oil of lubricating viscosity and a minoreffective amount of a molybdenum-amino-phosphorodithioate having stronginfrared absorption peaks at 680, 980, 1,165, 1,470 and 2,940 cm
 1. 4. Alubricating composition according to claim 1 wherein saidmolybdenum-amino-phosphorodithioate is less than about 10 percent byweight to the total composition.